TM 5-6675-320-14
r .
Main PCA A2 processor circuitry.
The plotter microprocessor is a 16-bit word
controller which essentially accesses and processes instructions from memory. It
also performs mathematical operations and controls the flow of data on the plotter
bus. The microprocessor circuitry also contains a clock generator, memory timing
a n d d e c o d i n g c i r c u i t s , b i d i r e c t i o n a l d r i v e r s , r e g i s t e r d e c o d e r s , a n d i n t e r r u p t a n d
s e l f t e s t r e g i s t e r s . R e f e r t o T a b l e 4 - 1 4 f o r m i c r o p r o c e s s o r d e f i n i t i o n s .
Table 4-14. MICROPROCESSOR DEFINITIONS
Mnemonic
Name
D e f i n i t i o n
SYNC
SYNCHRONOUS
A synchronizing signal generated by the
microprocessor denotes when microprocessor
i s i n a n i n s t r u c t i o n f e t c h c y c l e.
STM
START MEMORY
A signal generated by the microprocessor
which is essentially the system timing
s i g n a l . T h e s i g n a l s l e a d i n g e d g e i n d i-
cates that there is a stable address on the
b u s . W h e n t h e s i g n a l i s t r u e , i t i n d i c a t e s
a memory reference is in process.
UMC
SMC
PDR
RD
RAL
PON
INT
UNSYNCHRONOUS
MEMORY COMPLETE
SYNCHRONOUS
MEMORY COMPLETE
PROCESSOR DRIVING
A handshake signal indicating that a memory
or a register is ready to process data .
A signal generated by the microprocessor
when data, or an instruction, is on the
b u s . T h e t r a i l i n g e d g e i n d i c a t e s t h a t t he
microprocessor has accepted data. UMC must
be present for the microprocessor to gener-
ate SMC.
A signal generated by the microprocessor
denotes when the microprocessor is driving
the MOS bus.
READ
A microprocessor generated signal indicating
when memory is in a READ/WRITE state.
REGISTER ACCESS LINE
A microprocessor generated signal to decode
registers 20 - 27.
POWER ON
A power-up signal to the microprocessor.
Begins program execution at 408.
INTERRUPT
A signal from the interpolator section sig-
n i f y i n g i t i s r e a d y t o r e c e i v e n e w v e l o c i t y
data. The INT signal forces the micro-
processor to execute J S M 1 0 , I i n s t r u c t i o n .
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